Master Roshi, commonly referred to in the original Japanese as the Turtle Hermit (亀仙人 Kame-Sen'nin) and also known as Muten-Rōshi (武天老師 lit. Invincible Old Master), is a fictional character from the Dragon Ball series created by Akira Toriyama. He is called the Turtle Hermit due to the heavy turtle shells that he and his students would wear on their backs for weight training, Master Roshi is an ancient and wise martial arts master, as well as the innovator of the kamehameha technique. His students include Grandpa Gohan, The Ox-King, Son Goku, Krillin, Yamcha, and others.

Master Roshi is bald, with a thick van dyke beard and wears sunglasses, which he is almost never seen without. He wears beach clothes or martial arts suits, wields a walking stick, and during the earlier stages of the series, a turtle shell on his back. Unassuming yet wily, and physically frail at first glance, Master Roshi is depicted as a mighty warrior who constantly defies expectations in spite of his advanced age. He is considered a stock character, as he is both the elderly martial arts master and a source of comic relief whose lecherous behaviour is typical of dirty old geezer archetypes in shōnen manga. Roshi is known for his lewd actions throughout the series and is constantly ogling at young women on television exercise shows in his spare time or looking at pornographic magazines. He even bribes the young teen Bulma to show him her panties in exchange for a Dragon Ball earlier in the series. On the other hand, Master Roshi would be depicted as a very wise and compassionate person during the more serious moments in the series, who loves life and its simple pleasures, but is willing to make the ultimate sacrifice for his friends and students if necessary, such as when he risked his health and pushed his physical limits in order to perform the Mafuba technique (Evil Containment Wave in the English dub) against various opponents who could not be dispatched by conventional means.